This invention relates generally to a tower adapter, a method of producing a tower foundation and a tower foundation. In particular but not limited thereto, the present invention relates to a tower adapter for a wind turbine tower, a method for producing a foundation of a wind turbine tower, and a foundation of a wind turbine tower.
Several technical installations require a tower or a mast to which the installation is mounted. Non-limiting examples of such installations are wind turbines, antenna towers used in broadcasting or mobile telecommunication, pylons used in bridge work, or power poles. Typically, the tower is made of steel and must be connected to a foundation made of reinforced concrete. In these cases, the typical technical solution is to provide a flange with through-holes at the bottom of the tower. Anchor bolts are inserted into the through-holes and are fastened with nuts. Typically, the anchor bolts are connected to an anchor ring embedded in the foundation. Normally, the concrete surface of the foundation is relatively rough so that a grout joint is formed on which the flange is placed.
However, the bottom part of the tower has to be placed on the grout joint before the grout has finally cured. Therefore, a certain curing time of the grout joint has to be awaited after installing the bottom section of the tower until further sections of the tower can be installed. Typically, the curing of the grout takes at least 24 hours but may take even longer according to the conditions at the construction site. During this curing time of the grout joint, no further work can be done on the particular tower construction site. For example, the bottom section of a wind turbine tower is relatively large, typically about 10 m to 20 m long, and accordingly also relatively heavy. Therefore, the bottom section has to be transported in a horizontal position, e.g. to comply with the maximum headroom of bridges. Furthermore, two mobile cranes have to be used for lifting such a bottom section in a vertical position and placing it on the grout joint. However, after placing the bottom section on the grout joint the two mobile cranes are of no particular use until the grout joint has finally cured and further tower sections can be installed. Since mobile cranes are very expensive, it is economically detrimental if they are idle for longer times. Since the construction sites of wind turbines are often remote, it is also often economically detrimental to relocate the mobile cranes for the curing time of the grout joint.